If you have come across the work of Alice Miller, you will know that she is one of those "big ideas" people whose work is challenging and controversial but impossible to ignore. Alice Miller is to family psychology as Andrea Dworkin was to feminism. If the crude characterisation of Dworkin's position was that "all men are rapists", then the equivalent caricature of Miller's psychoanalytic view would be that "all children are abused by their parents".

With her first bestseller, The Drama of the Gifted Child, published a quarter of a century ago, Miller sent an entire generation into therapy when she wrote about how parents scar their children not only by glaring instances of cruelty and physical punishment but also through humiliation, neglect and inattention. Forthright and accessible, the book related how children protect themselves and their parents from the truth about the bad parenting they have received - even idealising their parents and striving painfully to earn their approval.

Miller's model of family relation ships has become a landmark for everyone from child-abuse professionals to the self-helping public. More than anyone else, Miller put people in touch with their "inner child", encouraging them to own "their own truth" - by which she meant the truth of their abuse.

The Drama of the Gifted Child was a word-of-mouth sensation, and went on to sell over a million copies. Since then, Miller has authored numerous follow-ups, whose titles speak for themselves - Thou Shalt Not Be Aware: Society's Betrayal of the Child, Banished Knowledge: Facing Childhood Injuries, The Truth Will Set You Free: Overcoming Emotional Blindness - to name a few. The latest, published next month, sticks to the eternal theme - The Body Never Lies: The Lingering Effects of Cruel Parenting.

The new book studies, in thumbnail-sketch fashion, the lives of several eminent artists - Arthur Rimbaud, Marcel Proust, Virginia Woolf, Friedrich von Schiller and others - and describes how the illnesses, mental disorders and addictions that ruined their lives can be traced to the cruelties they had suffered in childhood. The drama of the gifted child revisited - without the happy ending.

Now in her 70s, Miller lives in Switzerland. Although she has campaigned vigorously against smacking - penning "open letters" to the Pope and Tony Blair, among others - she is publicity-shy and shuns journalists. What we do know is that Miller was born in Poland in 1923, and settled in Switzerland in 1946, studying philosophy in Basle, then psychoanalysis in Zurich. She became a practising analyst herself, but resigned from the International Psychoanalytic Association in 1988 (signalling her "break" with mainstream Freudian analysis).

She has described her background as "ordinary middle-class" - "My father was an unsuccessful banker, my mother a housewife," she said in a rare interview in 1999. She has two (adult) children, about whom she has said: "I never hit them but I was sometimes careless and neglecting to my first child out of ignorance. Fortunately not so much as my parents had been to me. It is very painful to realise that, but this realisation can also be liberating from a self-deception."

Further biographical details are hard to obtain. According to one report, Miller was brought up in Germany, but how she and her family spent the wartime years is unknown. Whatever her personal experience, the spectre of Nazi persecution haunts the pages of her books. Elsewhere, she has analysed the psyches of Hitler and his henchmen, and despotism constantly recurs as a metaphor in her work. In the new book, she writes of her mother thus: "Not once did she apologise to me or express any kind of regret. She was always 'in the right'. It was this attitude that made my childhood feel like a totalitarian regime."

Strong stuff. And strong stuff is what you get with Alice Miller. It is practically impossible to read her, if you are a parent, without a gathering sense of unease, guilt and defensiveness. And you do not have to have been a vicious childbeater - Proust's mother was no worse than clinging and controlling, but it was enough, according to Miller, to condemn him to an untimely death.

It is much more comforting to identify with the child-victim. As the writer Daphne Merkin observed (in a critical review of Miller's 2002 book, The Truth Will Set You Free), The Drama of the Gifted Child was "cannily" titled - "presumably to flatter its readers". For who would not wish to think of themselves as gifted? This helps to explain the cult status the original book quickly achieved - because educated middle-class readers could easily find themselves reflected in it. Merkin went on to describe Miller as "the missing link between Freud and Oprah".

But that alone does not account for the huge impact of Miller's work. She was never merely a pop psychologist, even if she has a considerable talent for presenting psychoanalytic ideas in very clear, even stark terms. "She's extremely important," says psychologist Oliver James, author of They F*** You Up. "Clinically, she is almost as influential as RD Laing" - referring to the psychiatrist author of The Divided Self who completely overturned conceptions of mental illness in the 1960s. "Alice Miller changed the way people thought."

This rating is echoed by Terri Apter, professor of psychology at Cambridge University and author of You Don't Really Know Me (about relationships between mothers and daughters): "I'd put her alongside Laing as changing the way we see how an environment that often regards itself as benign can in fact be hostile or destructive."

To illustrate this point, Oliver James describes how, while working as a clinician in a psychiatric hospital in the early 1980s, he found himself treating a five-year-old girl who exhibited a disturbing degree of sexualised behaviour. He expressed his unease to a senior colleague, but his qualms were brushed off: "What do you expect? She's a little girl; you're a man." In other words, the standard Freudian line that the girl was simply acting out a fantasy of sexual union with a father figure. "Of course, what one would have done now is call in the police," says James.

By insisting on the reality of child abuse (sexual and otherwise), Miller became enormously influential with professionals in the field. Along with Jeffrey Masson, the analyst and writer who fell out with the Freud Archives where he had been director, Miller criticised Freud for his notorious U-turn of 1896 in which he rowed back from the obvious conclusion that incest and child sexual abuse was far more common than previously thought, and instead cast it as a complex of basic drives and fantasies inherent in the parent-child relationship. "He made a brilliant case," says James, "but unfortunately he was wrong."

"I do think she [Miller] was very important in the early 1980s," says Lynne Segal, professor of psychology and gender studies at Birkbeck College. But her enthusiasm is tempered. "In the 1970s, when the extent of child sexual abuse was being discovered by movements like feminism, the emphasis was on changing the world and empowering women. But in the 1980s, there was a narrowing down of psychoanalysis. The emphasis on childhood drama became very fashionable, but it was an individualisation of what cruelty meant - taking it out of any wider social and political realm."

Segal sees Miller as "one of the inaugurators of the trauma narrative" - the victim culture that not only gave us Dave Pelzer and a hundred other wannabe-bestselling memoirs of horrible childhoods, but also led to the wilder shores of regression therapy, rebirthing and recovered memory syndrome. Interestingly, Miller herself underwent and endorsed "primal therapy", in which patients were encouraged to regress to a childlike state in order to unlock their earliest experiences. She later distanced herself from its practitioners.

"She unforgettably focuses on a child's response to small, ordinary punishments," says Apter. Although "not a follower", Apter expresses a cautious enthusiasm for Miller's work. "She deals with very big questions about why people take pleasure in humiliating others. And she has very creative answers. The problem arises in how people respond to what she says because she's dealing with extreme cases."

But James admires the fact that she doesn't pull her punches: "She [Miller] is so ruthless and single-minded about it. Arguably, that's how you should be: if you confront the fact that you were fucked up, then you can deal with the fact that you fucked up your children."

In James's view, most of us probably need the shock treatment that Miller administers to jerk us out of our complacent ignorance of the child's subjective experience and the effect our parenting has. But he concedes that Miller's version of events leaves precious little space for DW Winnicott's notion of the "good enough" parent - and leaves us with very little idea, or hope, of avoiding destructive cycles of behaviour.

Miller is simply not in the parenting advice game. She is an evangelist, on a mission to redress the humiliation heaped on children. Her concept of psychotherapy is that the therapist is not the neutral sounding board of classical analysis, but an "advocate" or "enlightened witness" who is "partial" to the victim's point of view. And parents, in this narrative, are guilty until proven innocent.

Herein lies my own ambivalence towards Miller's message. If you can identify yourself as the child, then her work is richly suggestive; but if you come at it as a parent, Miller offers you nothing but guilt and anxiety. As Merkin puts it, "Miller's cartography" of family life is unrelentingly "bleak".

For Segal, though, it's not just a problem that Miller provides no practical guidance for parents on how to avoid the pitfalls; her whole vision of human relations is skewed. "What she does is reduce the complexities of children's emotions and the ambivalence of parents to a simple fairytale of good and evil," she says. "Masson was another who used to speak in terms of innocence and guilt - that Freud was 'guilty'. I would never want to use notions of innocence and guilt."

And blaming parents, she notes, nearly always boils down to blaming mothers. Segal prefers to see Miller's work in a broader context. In the beginning, it gained currency because it chimed with what feminism was saying about patriarchy and sexual exploitation, but then it allied itself with a kind of privatisation of unhappiness.

"Ultimately, it fed into a much more conservative climate that wanted to place the blame for all society's ills on bad parenting," she says. "It juxtaposed bad parents with the innocent child. It's too simple a story."

The Body Never Lies is unlikely to have the same impact that The Drama of the Gifted Child had. As Daphne Merkin notes: "With each book, her message gets slightly more attenuated." Miller has been banging the drum for truly empathetic childcare for more than 25 years, so perhaps it is not surprising if she sounds a little shrill nowadays. But as long as the issue of smacking keeps coming round, we will still need that voice.

· Alice Miller's book The Drama of the Gifted Child was published in the UK under the title The Drama of Being a Child.